It is well known that geothermal systems transfer heat or cool to homes and buildings by a heat pump, which is a mechanical device that transfers heat from one source to another. Ground-source units pull heat from the earth and transfer it to homes or buildings. Heat pumps provide both heating and cooling. The cooling process is simply the reverse of the heating process: heat is taken out of a building and returned to the Earth.
Typical ground-source heat pumps transfer heat using a network of tubes, called “closed loops.” These loops are filled with either water; heating, ventilating and air conditioning (HVAC) based chemicals or an anti-freeze solution. They run through the ground in the vicinity of a building and the liquid absorbs the riparian's heat energy. Then, the warmed liquid is pumped back through the system into the building. The process provides heat to the building space (i.e. heat transfers from the warmed liquid to the building space and results in relatively cooled liquid). Once the fluid passes through the building and transfers its heat energy, it flows through the loop system back to the riparian body and the two phase process (warming of liquid and heat transfer cooling of the warm liquid) recommences.
In warm weather, these systems “reverse” into cooling mode. Technically, the system does not “run backwards.” Instead, a series of valves enables the system to switch the “hot” side and the “cold” side. The heat from the building is transferred to the liquid in the loop and the resulting warmed liquid is pumped back into the ground for cooling. When the ground source heat pump is in cooling mode, it usually has an excess of warmed liquid in the system. The warmed liquid can be used to heat water for the building and eliminate the use of a hot water heater to heat water for the building.
Currently, traditional heating systems rely on combustion (the burning of fuel) either on site or at the power plant. Fuel-powered heating units, such as gas and boiler systems, burn fuel at the site to produce heat energy. Electric-powered heating and cooling systems do not require combustion at the site of the furnace; instead, the combustion occurs at power plants. In 1998, approximately 80% of the electricity in the United States was produced by burning fossil fuels. The by-products produced by combustion systems contain harmful emissions. These emissions degrade air quality and negatively impact individuals' health and contribute to environmental problems (e.g., acid rain and the greenhouse effect). For the health of individuals and communities throughout the world, it makes sense to develop heating and cooling technologies that reduce or eliminate fossil fuel combustion.
Conventional models of geothermal energy systems address homes, businesses, individual areas and municipalities on an isolated implementation basis. Schools facing skyrocketing energy bills are searching for cost-effective alternatives. Geothermal systems represent a proven option. In addition, they utilize a renewable energy source, the Earth's naturally occurring heat energy. In Wisconsin, four school districts recently installed geothermal systems at area schools. District administrators were impressed by geothermal energy efficiency and its ability to yield long-term cost savings.
Existing conventional uses of geothermal energy systems have limitations in distribution and deployment. Each business or home owner digging his/her own underground coil, piping or closed loop system, has to pay the up front cost of work required in implementing a geothermal system. The costs may be insurmountable for many families, businesses, and municipalities. Some homes or businesses are precluded from digging the geothermal underground network system due to zoning, topographic, space or geologic factors that appear on potential geothermal system user's land sites. Moreover, the energy exchangers (e.g., heat pumps) that make up the geothermal energy system are being powered by electrical energy received from traditional power plant.